1. Virtual Private Network VPN

1.1 Definition

Virtual private networks are often referred to as VPNs. The VPN service enables the connectivity of several private networks via a shared public infrastructure. The main purpose of a VPN service is to facilitate internal communications within a multi-site company, and communications between partner companies (customers, suppliers). Before IP technologies became widespread, this service was provided over X25, Frame-Relay or ATM-type networks.

The characteristics of a virtual private network must be compared with those of a truly private network in terms of throughput, latency, jitter, reliability and security.

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